At the present time, it is becoming increasingly the normal practice in the retail sales industry to use what is called "point of sales" packaging for the majority of products offered for sale in retail outlets. This practice is forcing the packaging industry to both develop and implement equipment and practices which will provide an improvement in the quality of printing. In other words, the former "brown box" is now bursting with color and more complex graphics are making the product packages a "selling tool." This is particularly the situation being encountered in the corrugated box industry.
Unfortunately, there are a significant number of variables encountered in a printing arrangement which can adversely affect the quality of the finished printed product. Although not necessarily limited thereto, these variables include the following, the parallelism, within acceptable tolerances, between the anilox roll and the printing plate cylinder as well as the parallelism between the impression cylinder and such printing plate cylinder; establishment of the zero point, i.e., the point at which the cylinders are properly spaced from one another; synchronization between the rotational speed of the working surface of the printing plate cylinder and the surface of the substrate to be printed thereon; and, various print characteristics which are well known in the art. Such print characteristics encountered in a print arrangement at least include: screens, positive and reverse graduated type; bar codes; solids; impression; slippage; and, distortion.
Prior to the present invention, it has been taught in U.S. Pat. No. 2,994,964 to use a transparent gauge for aligning the paper and/or metal master plate onto the working surface of a print cylinder disposed in an offset printing press. This transparent gauge is adjustably secured to a bar member that, in turn, is attached to the frame which supports such print cylinder. The bar member enables such gauge to be moved in a lateral manner across the printing plate to be registered in the press, if and when different sized master plates are required to be aligned. In addition, it can be seen that such transparent gauge is hinged along its midsection. The purpose of the hinged connection is to allow the gauge to be readily moved out of position after registry has been achieved so as not to unduly hinder observation of the printing operation by the press operator.
In addition, U.S. Pat. No. 3,099,092 teaches a gauge useful in verifying the position of registry marks which are located on a printed sheet. This prior art gauge includes a member having one end portion of plate-like shape. Such plate-like shaped member is adapted for insertion under the edge of a printed sheet. Such printed sheet being provided with registry marks located along the margin width. Such gauge includes another end portion that is provided with a plurality of parallel guide means and a positioning abutment extending transversely of such guide means. The one end portion is marked with a linear scale of preselected margin widths. Such margin widths being measured from the abutment. A plurality of relatively spaced parallel slides are slidably adjustable in such guide means, respectively, above such end portion. Such parallel slides are made from a transparent material. Each such parallel slide being provided with a mark that is adapted to be positioned in register with a selected indicia of such linear scales and, thereafter, applied to register marks, respectively, of such printed sheet. An edge of such printed sheet being interposed between such member and such slide and against the abutment. In this manner, the position of such register marks on such printed sheet can be verified.
The prior art further teaches in U.S. Pat. No. 4,469,025 a device useful in film-mounting print control strips at a precise level and in registry. According to this invention, this device consists of a foil forming a template for a mounting foil used when mounting a print control strip. Such foil template contains the ink as well as the measuring-field information that is required for film mounting at a precise level and in good registry. Further, this device includes a characteristic representation of the printing plate center.
Finally, a method of and an apparatus for measuring and correcting register error that are often encountered in multi-color printing equipment is taught in U.S. Pat. No. 4,827,626. In this prior art method and apparatus, a multi-color sheet that has been printed, having register marks for each color is placed on a measuring table. The approximate location of the register pairs and the accurate spacings of the individual register marks in each pair are then determined by one of a light stylus, an electronic color video measuring camera system or on a measuring table equipped with a digitizer surface. The values obtained by one of these pieces of equipment are entered into a computer. Such computer then calculates the corrective values to be used to reposition one or more of the printing plates being carried by the working surface of each printing plate cylinder to achieve the required color registry in a multi-color printing arrangement.
As will be readily understood and recognized by persons skilled in the printing art, however, none of the above-discussed references, either singularly or taken in combination, are capable of meeting the performance or objectives of the present invention to be discussed hereinafter.